溴化丁基橡胶／C5石油树脂复合材料的制备及性能研究

在溴化丁基橡胶（BIIR）中添加了不同用量的C5石油树脂（以下简称G）,通过模压硫化制备了BIIR／C5复合材料。采用无转子硫化仪、门尼粘度仪、扫描电子显微镜（SEM）和动态热力学分析仪（DMA）等研究了C5含量对BIIR／Cs复合材料的结构与性能的影响。研究结果表明,随着C5用量的增加,BIIR／G复合材料正硫化时间（t90）略有延长,交联程度及门尼粘度下降,加工性提高,损耗峰呈现单峰状,不断向高温偏移,损耗因子（tanδ）峰值及峰面积不断增大,且有效阻尼温域（tan δ≥0．3）大幅度扩宽;拉伸强度、撕裂强度及硬度和冲击回弹率不断下降,断裂伸长率增大,但复合材料在G用量为5～10phr时仍能保持较高的力学强度。     

Effect of crosslink structures on dynamic mechanical properties of natural rubber vulcanizates under different aging conditions

The effects of crosslink structures on the dynamic mechanical properties (DMPs) of unfilled and carbon black N330‐filled natural rubber (NR) vulcanizates cured with conventional (CV), semiefficient (SEV), and efficient (EV) cure systems and having about the same total crosslink densities were investigated before and after aerobic and anaerobic aging at 100°C. The three unfilled NR vulcanizates cured with the CV, SEV, and EV systems had about the same mechanical loss factor (tan δ) values at about 0°C but showed some apparent differences in the tan δ values in the order EV > SEV > CV at relatively high temperatures of 40–80°C before aging. However, N330‐filled NR vulcanizates gave higher tan δ values than the unfilled vulcanizates and showed little effect of the crosslink types on the tan δ at different temperatures over the glass‐transition temperature (T_g) before aging. Aerobic heat aging increased the T_g and tan δ values of the vulcanizates over a wide range of temperatures from ?80 to 90°C that was mainly due to the changes in the total density and types of crosslinks. The unfilled vulcanizates cured with the CV system showed the greatest change in DMP because of their poor resistance to heat aging. Aerobic heat aging of NR vulcanizates caused a more significant change in the DMP than anaerobic heat aging because of the dominant effect of the oxidative degradation during aerobic heat aging on the main‐chain structure, crosslink structures, and DMPs of the vulcanizates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 710–718, 2001     

Influence of 1,2‐polybutadiene on properties of dicumyl peroxide cured brominated butyl rubber

Peroxide curing of brominated butyl rubber (BIIR) is an attractive topic, but the degradation of BIIR during the curing is a drawback needed to be overcome. Coagent assisted peroxide curing system is an attractive and effective choice in order to increase the crosslink density of rubbers. 1,2‐polybutadiene (1,2‐PB) is used as a crosslinking coagent for the curing of BIIR by dicumyl peroxide (DCP), and the effect of 1,2‐PB on the curing characteristics, crosslink density, and mechanical properties is investigated. The addition of 1,2‐PB affects the curing characteristics of BIIR compound and significantly increases the crosslink density of BIIR vulcanizates. With increasing 1,2‐PB content, the tensile strength and stresses at a given extension of BIIR vulcanizates increase, but the elongation at break decreases. A stress‐softening effect of the carbon black filled BIIR vulcanizates is observed and becomes more pronounced with increasing 1,2‐PB content. The addition of 1,2‐PB increases the stress relaxation index of BIIR. GPC and ¹³C‐NMR results indicate 1,2‐PB participates in the crosslinking reaction, and the existence of 1,2‐PB component in the insoluble fraction of BIIR/1,2‐PB vulcanizates is confirmed by solid‐state ¹³C‐NMR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43280.     

Effect of tackifiers on mechanical and dynamic properties of carbon‐black‐filled NR vulcanizates

This work focuses on the effect of tackifiers on mechanical and dynamic properties of carbon‐black‐filled vulcanizates. Three types of tackifiers with difference in softening points are selected for study including petroleum resin, phenolic resin, and gum rosin. The effect of tackifiers on the retardation of vulcanization is observed and the changes in mechanical properties due to the reduction in crosslink density are correlated. Good compatibility between natural rubber and all three tackifiers is verified by a single tan‐delta peak detected for each vulcanizate in temperature ramp test. A similar behavior to the Payne effect which usually found in the case of particulate‐filled rubbers is observed for the tackifier‐filled counterparts. The variation of temperature plays a crucial role in the dynamic behavior of tackified vulcanizates since the state of tackifiers determines its function during dynamic straining. As temperature passed through the softening point of a particular tackifier, substantial reduction in elastic response is observed; however, its relative damping to the untackified may still be maintained. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.     

Effect of lactic acid chain length on thermomechanical properties of star‐LA‐xylitol resins and jute reinforced biocomposites

Star‐shaped bio‐based resins were synthesized by direct condensation of lactic acid (LA) with xylitol followed by end‐functionalizing of branches by methacrylic anhydride with three different LA chain lengths (3, 5 and 7). The thermomechanical and structural properties of the resins were characterized by ¹³C NMR, Fourier transform IR spectroscopy, rheometry, DSC, dynamic mechanical analysis (DMA), TGA and flexural and tensile tests. An evaluation of the effect of chain length on the synthesized resins showed that the resin with five LAs exhibited the most favorable thermomechanical properties. Also, the resin's glass transition temperature (103 °C) was substantially higher than that of the thermoplast PLA (ca 55 °C). The resin had low viscosity at its processing temperature (80 °C). The compatibility of the resin with natural fibers was investigated for biocomposite manufacturing. Finally, composites were produced from the n5‐resin (80 wt% fiber content) using jute fiber. The thermomechanical and morphological properties of the biocomposites were compared with jute‐PLA composites and a hybrid composite made of the impregnated jute fibers with n5 resin and PLA. SEM and DMA showed that the n5‐jute composites had better mechanical properties than the other composites produced. Inexpensive monomers, good thermomechanical properties and good processability of the n5 resin make the resin comparable with commercial unsaturated polyester resins. © 2017 Society of Chemical Industry     

Dynamic mechanical properties in blends of poly(styrene‐b‐isoprene‐b‐styrene) with aromatic hydrocarbon resin

The damping properties in blends of poly(styrene‐b‐isoprene‐b‐styrene) (SIS) and hydrogenated aromatic hydrocarbon (C₉) resin were investigated by dynamic mechanical analysis. SIS exhibited two independent peaks of loss factor (tan δ) corresponding to the glass transition of polyisoprene (PI) and polystyrene (PS) segments, respectively. The addition of hydrogenated C₉ resin had a positive impact on the damping of SIS. With the increasing softening point and content of the resin, the main tan δ peak shifted to higher temperatures and the useful damping temperature range was broadened. Addition of mica or PS was found to widen the effective damping range evidently in the high‐temperature region, especially when PS was mixed in the solid state. It was concluded that the dispersed PS domains played a role of reinforcing fillers at low temperatures and served as a polymer component with a tan δ peak due to its glass transition at the high temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4157–4164, 2006     

Comparison of thermal techniques for glass transition measurements of polystyrene and cross-linked acrylic polyurethane films

There are few quantitative comparisons in the literature between glass transitions (T_g) measured by differential scanning calorimetry (DSC) and by dynamic mechanical analysis (DMA). Also, in the case of DMA, two different operational definitions have been used to obtain the glass transition, namely, the loss modulus (E″) and damping (tan δ) peak temperatures. We propose a new DMA definition of T_g and demonstrate that it agrees with DSC T_g measurements within ±2°C for both thermoplastic polystyrene and thermoset cross-linked acrylic polyurethane films with measurable tan δ peaks. The glass transitions for a single polystyrene standard and several cross-linked acrylic polyurethane films were measured by DSC. Additionally, E″ and tan δ peak temperatures were measured by DMA as a function of frequency and temperature. Empirically, it was determined that the average of the E″ and tan δ peak temperatures measured at 1 rad/s oscillation frequency corresponds to the glass transition measured by the ASTM E1356 DSC test method. © 1994 John Wiley & Sons, Inc.     

Elucidation of segmental relaxations of silica-filled cis-polybutadiene rubber composites

There has been a lot of interest in characterizing polymer chain dynamics of rubber compounds because it is thought to underpin the exceptional mechanical properties of composites. We studied the effect of precipitated silica on segmental mobility of cis-polybutadiene rubber by using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). It was found that the calorimetric glass and melting transitions of silica-filled master batch materials were essentially identical to those of the gum rubber, showing no dependence of silica loading and silane treatment. And, we observed in calorimetric measurement a change in the melting transition step for the vulcanizates. The results were correlated to the change of chemical crosslinks caused by various factors filler agglomeration and adsorption effect that tended to decrease chemical crosslink density and silane modification increased it. The DMA results demonstrated that the second peak in loss modulus versus temperature curve for the quenched vulcanizates was assigned to melting peak, and this peak disappeared at a slow cooling rate, which coincided well with DSC results. Moreover, crystalline parts constrained amorphous regions such that the glass transition temperature was raised for the cooled vulcanizates with high chemical crosslinks.     

High internal phase emulsion foams: Copolymers and interpenetrating polymer networks

High internal phase emulsion (HIPE) copolymer and interpenetrating network foams were prepared from 2‐ethylhexyl acrylate (EHA), styrene (S) and divinylbenzene (DVB) using a unique process. The morphologies, thermal properties and dynamic and static mechanical properties of these foams were investigated. The glass transition temperatures and damping properties of the EHA/S copolymer foams vary with its composition. IPN foams with very broad tan 5 peaks were obtained. The damping properties of IPN foams were tailored through changing copolymer composition and monomer composition. The IPN foams based on a copolymer foam and styrene had a broader tan δ peak, a higher glass transition temperature and a higher modulus than tne copolymer foams of similar overall styrene contents. It is therefore possible to prepare novel damping foams based on polyHIPE foams through the synthesis of interpenetrating polymer networks.     

Influence of vinyl ester/styrene network structure on thermal and mechanical behavior

The influence of vinyl ester/styrene network structure on thermal and mechanical properties was investigated. The crosslink density of the resins was altered by changing the molecular weight of the vinyl ester oligomer and by varying the amount of styrene used during the crosslinking reaction leading to variations in both the physical network structure and the chemical composition of the polymeric networks. The glass transition temperatures of the network polymers were found to increase systematically with increasing crosslink density without the additional influence of the chemical composition as determined from both differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The breadth of the glass transition regions increased with crosslink density for the DSC data, but the breadth assessed from the DMA data did not vary significantly for the network materials. A secondary relaxation was observed for the materials using DMA, and this relaxation did not appear to be significantly affected by changes in either the crosslink density or the composition of the network. Cooperativity studies involving time–temperature scaling of dynamic mechanical data in the glass formation temperature region were also conducted. The degree of segmental cooperativity at T_g appeared to be primarily influenced by the chemical composition of the networks. These issues dealing with the structure of the networks provided insight into the associated fracture properties in the glassy state (ambient temperature). Specifically, an empirically based linear correlation was found between the fracture toughness of the networks and the cooperative domain size at the glass transition temperature normalized by the crosslink density. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 917–927, 2001     

双酚A型苯并恶嗪/酚醛体系固化物的性能研究

将双酚A型苯并恶嗪(BOZ-a)和线形酚醛树脂按照不同的配比进行共混固化,制备了浇铸体(BPx,x表示线形酚醛在共混树脂中的质量分数)。采用力学性能,吸水性测试,动态热机械分析和热重分析研究了酚醛树脂含量对浇注体性能的影响。结果表明,随着共混体系中酚醛树脂含量的增加,浇铸体弯曲强度呈下降趋势,玻璃化转变温度及交联密度也逐渐降低,但弯曲模量、初始储能模量、硬度和热稳定性均呈先上升后下降的趋势,而吸水率呈先减小后增加的趋势。BP20体系综合性能优良,初始模量最大,达到7.384 GPa,玻璃化转变温度为168℃,7 d吸水率为0.116%,5%热失重温度为285℃。     

反式-1，4-聚异戊二烯硫化胶及其共混硫化胶的研究

研究了反式－１，４－聚异戊二烯（ＴＰＩ）硫化胶及其与ＢＲ，ＳＢＲ，ＮＲ共混硫化胶的性能。结果表明，通过控制硫黄用量即交联密度，可使ＴＰＩ硫化胶具有优异的力学和动态力学性能；ＴＰＩ与ＢＲ，ＳＢＲ，ＮＲ共混，工艺性能良好，当ＴＰＩ／ＢＲ，ＴＰＩ／ＳＢＲ和ＴＰＩ／ＮＲ共混比小于５０／５０时，共混硫化胶的力学和动态力学性能优于ＢＲ，ＳＢＲ和ＮＲ硫化胶，特别是拉伸疲劳寿命大大延长，这正是高性能轮胎所需要的     

Correlations between dynamic mechanical properties and nodular morphology of cured epoxy resins

Various epoxy resin formulations, based on the diglycidyl ether of bisphenol A (DGEBA) and cured with diethylene triamine (DETA) were studied. Dynamic mechanical measurements were used to characterize changes in mechanical properties as a function of temperature. The morphology of the cured resins was investigated by transmission electron microscopy. Correlations between dynamic mechanical properties and morphology were described and discussed by applying the concept of inhomogeneous (nodular) thermoset morphology. The elastic storage modulus in the glassy state was determined primarily by the internodular matrix, whereas the glass transition of cured resins depended upon the intranodular crosslink density.     

Influence of cure schedule and solvent exposure on the dynamic mechanical behavior of a vinyl ester resin containing glass fibers

This study deals with the dynamic mechanical properties of a glass-reinforced vinyl ester resin. The viscoelastic parameters of the loss factor and the storage modulus as a function of the cure temperature were used as a criterion to determine the optimum cure conditions to be employed. It is shown that the cure temperature usually used to cure these resins is not enough to reach the maximum glass transition temperature, and, therefore, an additional postcure should be used. The influence of several solvents on the dynamic mechanical behavior of these resins cured following the cure pathway proposed by the supplier was also analyzed. This behavior was compared with the solvent uptake at various exposure times, and the changes observed were related to the crosslink density as well as to the chemical structure of both the resin and the solvent. Finally, the effects of varying the exposure temperature were also investigated for the resin exposed to a liquid which simulates petroleum fluid. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2595–2602, 1998     

Damping analysis of polyurethane/polyacrylate interpenetrating polymer network composites filled with graphite particles

The graphite‐filled polyurethane/poly(methyl methacrylate‐butyl methacrylate) (PU/P(MMA‐BMA)) semi‐interpenetrating polymer networks (IPNs) were synthesized by sequential method. The influences of graphite particle content and size on the 60/40 PU/P(MMA‐BMA) IPNs were studied. The damping properties of IPN composites were evaluated by dynamic mechanical thermal analysis (DMA) and cantilever beam resonance methods. The mechanical performances were investigated using tensile and hardness devices. DMA results revealed that the incorporation of graphite particles improved damping properties of IPNs significantly. The 5% graphite‐filled IPN composite exhibited the widest temperature range and the highest loss factor (tan δ) when the test frequency was 1 Hz. As to the damping properties covering a wide frequency range from 1 to 3,000 Hz, the addition of graphite particles broadened the damping frequency range (Δf, where tan δ is above 0.3) and increased the tan δ value of IPNs. Among them, the composite with 7.5% graphite showed the best damping capacity. And the hardness and the tensile strength of IPN composites were also improved significantly. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers     

A novel condensation-addition-type phenolic resin (MPN): Synthesis, characterization and evaluation as matrix of composites

This paper reports a novel methylol and propargyl-containing dual-cure-mechanism novolac-based phenolic resin (MPN). MPN resins with varying contents of reactive groups were synthesized by a two-step one-pot method facilly and characterized by Flourier transfer infrared spectra (FT-IR), hydrogen magnetic resonance spectra (¹H NMR), gel permeation chromatography (GPC), dynamic scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) techniques. The resins could be thermally cured by two gradual but fused stages: Condensation of methylol groups and addition polymerization of propargyl groups. This novel resin has advantages over conventional condensation-cure and addition-cure phenolic resins in processing capability. The results of DMA and thermogravimetry analysis (TGA) showed the cured resins possessed high thermal properties. Evaluation of MPN as matrices for advanced composites indicated the enhanced crosslink network derived from dense reactive groups in one single molecule was beneficial to the admirable thermal stability, but was detrimental to the mechanical properties of the resultant composites. MPN resin was amongst ideal candidates for matrices of high temperature materials.     

Interaction Between Fumed-Silica and Epoxidized Natural Rubber

Epoxidized natural rubber (ENR)/fumed silica vulcanizates were prepared by mechanical mixing method. Fumed silica content can affect mechanical properties of the composites, and ten parts per hundreds of rubber (phr) fumed silica lead to the best tensile strength. The interaction between ENR and fumed silica was characterized by Kraus equation, crosslink density (tested by NMR), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and scanning electron microscope (SEM). The results showed that the dispersion of silica in ENR was better than in natural rubber (NR), hydrogen bond was produced between ENR and fumed-silica in ENR/silica blends, and glass transition temperature of ENR/silica vulcanizate was higher than pure ENR vulcanizate. TGA and DMA confirmed that there was intense interaction between ENR and silica.     

树脂对硅橡胶性能的影响

研究了PS树脂、2112树脂、C5/C9石油树脂等3种树脂时硅橡胶混炼胶力学性能和阻尼性能的影响.结果表明,加入PS树脂可提高硅橡胶的力学性能,加入C5/C9石油树脂或2112树脂对硅橡胶力学性能无明显影响;加入C5/G9石油树脂和2112树脂对硅橡胶阻尼性能无明显影响,但加入PS树脂对硅橡胶高温阻尼性能有一定改善作用;加入C5/C9石油树脂和2112树脂对硅橡胶的高低温模量变化影响不大,但加入PS树脂使硅橡胶的高低温模量变化超过2个数量级,影响其模量稳定性,不利于在高低温环境下减振材料的实际应用.     

二烯丙基双酚A催化改性酚醛型氰酸酯树脂的催化固化

研究了二烯丙基双酚A（DBA）催化改性酚醛型氰酸酯树脂（cy-5）,通过差示扫描量热法（DSC）、热重分析（TG）、冲击性能和动态热机械分析（DMA）测试,分析了改性树脂的热性能和力学性能。研究表明：DBA对cy-5有催化和增韧的双重作用,当DBA的添加量为5%（质量分数）时,催化效果最为明显,含10% DBA的改性树脂固化物的冲击强度达到7.41 kJ/m2,改性树脂固化物的玻璃化转变温度（Tg）和储能模量（E'）均有所降低,但幅度不大。     

Damping mechanism and different modes of molecular motion through the glass transition of chlorinated butyl rubber and petroleum resin blends

To further investigate the effect of petroleum resin on damping mechanism and different modes of motion of chlorinated butyl rubber (CIIR), two kinds of petroleum resins with different molecular structures, aliphatic C5 resin and aromatic C9 resin, were incorporated into CIIR. The experimental results showed that the aliphatic C5 resin exhibited a better miscibility with CIIR, compared with aromatic C9 resin. With increase in the content of the C5 resin, the α process and the α′ process of CIIR moved to the higher temperature but to different extents, and the effective damping temperature range was broadened remarkably. The CIIR/C9 resin blends showed two loss peaks, which corresponded to the CIIR matrix and the C9 resin dispersed phase, respectively. The C9 resin neither moved different relaxation modes of CIIR to room temperature nor enhanced the value of the loss damping peak. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40464.